[all-commits] [llvm/llvm-project] 23d45e: [MCP] Remove dead copies from basic blocks with su...

[Craig Topper via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: 23d45e55edb0ca4567f5876e7051ff4a649213df
      https://github.com/llvm/llvm-project/commit/23d45e55edb0ca4567f5876e7051ff4a649213df
  Author: Craig Topper <craig.topper at sifive.com>
  Date:   2024-03-28 (Thu, 28 Mar 2024)

  Changed paths:
    M llvm/lib/CodeGen/MachineCopyPropagation.cpp
    M llvm/test/CodeGen/AArch64/machine-cp-sub-reg.mir
    M llvm/test/CodeGen/AArch64/ragreedy-local-interval-cost.ll
    M llvm/test/CodeGen/AMDGPU/atomic_optimizations_pixelshader.ll
    M llvm/test/CodeGen/PowerPC/stack-restore-with-setjmp.ll
    M llvm/test/CodeGen/Thumb2/aligned-nonfallthrough.ll
    M llvm/test/CodeGen/Thumb2/mve-gather-increment.ll
    M llvm/test/CodeGen/Thumb2/mve-gather-scatter-optimisation.ll
    M llvm/test/CodeGen/Thumb2/mve-laneinterleaving-reduct.ll
    M llvm/test/CodeGen/Thumb2/mve-postinc-lsr.ll
    M llvm/test/CodeGen/Thumb2/mve-vldst4.ll
    M llvm/test/CodeGen/X86/optimize-max-0.ll
    M llvm/test/CodeGen/X86/tls-loads-control3.ll

  Log Message:
  -----------
  [MCP] Remove dead copies from basic blocks with successors. (#86973)

Previously we wouldn't remove dead copies from basic blocks with
successors. The comment said we didn't want to trust the live-in lists.
The comment is very old so I'm not sure if that's still a concern today.

This patch checks the live-in lists and removes copies from
MaybeDeadCopies if they are referenced by any live-ins in any
successors. We only do this if the tracksLiveness property is set. If
that property is not set, we retain the old behavior.



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